SPATIAL AND TEMPORAL INTERACTIONS OF ELK, MULE DEER, AND CATTLE
Priscilla K. Coe
Research Wildlife Biologist, Oregon Department of Fish and Wildlife
1401 Gekeler Lane, La Grande Oregon 97850, phone (541-962-6550), fax (541-962-6504),
email pcoe@eou.edu,
Bruce K. Johnson
Project Leader, Oregon Department of Fish and Wildlife
1401 Gekeler Lane, La Grande, Oregon 97850, phone (541-962-6556), fax (541-962-6504),
email johnsobd@eou.edu,
Kelley M. Stewart
Ph.D. Candidate, Institute of Arctic Biology and Department of Biology and Wildlife, University
of Alaska Fairbanks, Fairbanks, Alaska 99775, phone (907-474-7172),
email ftkms1@uaf.edu, and
John G. Kie
Research Wildlife Biologist, USDA Forest Service, Pacific Northwest Research Station
La Grande, Oregon 97850, phone (541-962-6529), fax (541-962-6504),
email jkie@fs.fed.us
Forested rangelands in the western U.S. typically support elk (Cervus elaphus) and mule deer
(Odocoileus hemionus) year-round and free-ranging livestock during late spring, summer, and
autumn. We documented interactions among these species in relation to how they distributed
themselves over the landscape throughout the grazing season
(April – October). Understanding the influence of each ungulate species on the other is a vital
link to understanding population productivity and nutritional status across seasons. Elk, mule
deer, and cattle interactions were analyzed in the Main Area (7760 ha), Smith-Bally pasture (a
sub-pasture of the Main Area; 2400 ha) and the Northeast Area (1453 ha) of Starkey
Experimental Forest and Range, northeastern Oregon. For our analysis we used subsets of
>100,000 locations from radio-collared female elk, mule deer, and cattle between 1993 and
1996. Our results showed 1) spatial partitioning between elk and mule deer on a 38-75 day
(spring) temporal window in Main Area; 2) avoidance and shifts in use of pastures and plant
communities by both elk and mule deer in response to cattle on a 16-38 day (early and late
summer) temporal window in Smith-Bally pasture; 3) strong inter-specific avoidance among all
3 ungulates on a 6-hour temporal window during spring, summer, and autumn in Northeast Area;
and 4) competitive displacement of elk by cattle with a corresponding displacement of mule deer
by elk during early summer. Analysis of resource selection functions indicated that niche
partitioning among species became less pronounced as summer progressed and animals
converged on areas where quality and quantity of forage was highest. We recommend that
methods to predict and map ungulate distributions for management purposes take into account
spatial and temporal interactions as well as competitive cascades among those species.